Controlling high quality manufacturing processes: a robustness study of the lower-sided tbe ewma procedure

Download
index.pdf
2008
Pehlivan, Canan
Show full item record
224
views
92
downloads
In quality control applications, Time-Between-Events (TBE) type observations may be monitored by using Exponentially Weighted Moving Average (EWMA) control charts. A widely accepted model for the TBE processes is the exponential distribution, and hence TBE EWMA charts are designed under this assumption. Nevertheless, practical applications do not always conform to the theory and it is common that the observations do not fit the exponential model. Therefore, control charts that are robust to departures from the assumed distribution are desirable in practice. In this thesis, robustness of the lower-sided TBE EWMA charts to the assumption of exponentially distributed observations has been investigated. Weibull and lognormal distributions are considered in order to represent the departures from the assumed exponential model and Markov Chain approach is utilized for evaluating the performance of the chart. By analyzing the performance results, design settings are suggested in order to achieve robust lower-sided TBE EWMA charts.
Industrial engineering.
http://etd.lib.metu.edu.tr/upload/12609937/index.pdf
https://hdl.handle.net/11511/17912
Graduate School of Natural and Applied Sciences, Thesis

Suggestions

Managing production and lead time quotation with multiple demand classes
Sayın, Ece; Savaşaneril Tüfekci, Seçil; Department of Industrial Engineering (2010)
In this study, we investigate several facets of a due-date quotation problem and develop a model considering jointly due-date quotation, order acceptance and base-stock decisions in a hybrid make-to-stock (MTS) / make-to-order (MTO) and multi-class system with lead time sensitive Poisson demand and exponentially distributed service times. We seek to maximize profit considering lateness penalties and holding costs in the model. We consider three alternative due-date quotation policies each having different p...
Monitoring high quality processes: a study of estimation errors on the time-between-events exponentially weighted moving average schemes
Özsan, Güney; Köksal, Gülser; Department of Industrial Engineering (2008)
In some production environments the defect rates are considerably low such that measurement of fraction of nonconforming items reaches parts per million level. In such environments, monitoring the number of conforming items between consecutive nonconforming items, namely the time between events (TBE) is often suggested. However, in the design of control charts for TBE monitoring a common practice is the assumptions of known process parameters. Nevertheless, in many applications the true values of the proces...
On the service models for dynamic scheduling of multi-class base-stock controlled systems
Kat, Bora; Avşar, Zeynep Müge; Department of Industrial Engineering (2005)
This study is on the service models for dynamic scheduling of multi-class make-to-stock systems. An exponential single-server facility processes different types of items one by one and demand arrivals for different item types occur according to independent Poisson processes. Inventories of the items are managed by base-stock policies and backordering is allowed. The objective is to minimize base-stock investments or average inventory holding costs subject to a constraint on the aggregate fill rate, which is...
A lagrangean heuristic for the two-stage modular capacitated facility location problem
Sevinç, Selim; Meral, Fatma Sedef; Department of Industrial Engineering (2008)
In this study, a Lagrangean heuristic based on Lagrangean relaxation and subgradient optimization is proposed for the two-stage modular capacitated facility location problem. The objective is to minimize the cost of locating and operating plants and warehouses, plus the cost of transporting goods at both echelons to satisfy the demand of customers. The difference of our study from the two-stage capacitated facility location problem is the existence of multiple capacity levels as a candidate for each plant i...
Interval priority weight generation from interval comparison matrices in analytic hierarchy process
Öztürk, Ufuk; Karasakal, Esra; Department of Industrial Engineering (2009)
In this study, for the well-known Analytic Hierarchy Process (AHP) method a new approach to interval priority weight generation from interval comparison matrix is proposed. This method can be used for both inconsistent and consistent matrices. Also for the problems having more than two hierarchical levels a synthesizing heuristic is presented. The performances of the methods, interval generation and synthesizing, are compared with the methods that are already available in the literature on randomly generate...
Citation Formats
C. Pehlivan, “Controlling high quality manufacturing processes: a robustness study of the lower-sided tbe ewma procedure,” M.S. - Master of Science, Middle East Technical University, 2008.
METU IIS - Integrated Information Service open@metu.edu.tr